Installation manual
PSC1-C-10 Installation manual V2.6
Page 160 of 173
Version: 57E
12.3.5.3
Consideration of systematic failures
In addition, systematic failures are also to be considered in the hardware specification.
Example of measures against systematic failures:
Loss of power during operation. If there is a hazard here, a power loss must be considered like an
operating state. The SRP/CS must control this state such that the safe state is retained.
Measures against systematic failures according to Annex G DIN EN ISO 13849-1:
Source BGIA Report 2/2008
Fault exclusions:
If there are fault exclusions for certain devices or system components, these are to be stated and
specified in detail.
Fault exclusions can be, e.g. mech. shaft fracture, sticking switching contacts, short-circuits in cables
and wires etc.
The admissibility of the fault exclusions is to be justified, e.g. by referencing permissible fault
exclusions according to applicable standards e.g. EN ISO 13849-1)
If special measures are necessary for these fault exclusions, these are to be stated.
Examples for fault exclusions and measures assigned:
•
Positive locking connection on mech. shaft connections
•
Dimensioning based on adequate theoretical principles related to fracture of components in
the safety chain
•
Positive guidance in conjunction with positive separation on sticking of switching contacts
•
Protected laying within the switchgear to avoid short-circuits in cables and wires, as well as
laying cables in cable ducts
